The invention relates to a method of applying an embossing foil to a flexible portion of material such as a strip or web of material. Such a foil comprises for example a decorative or textured layer or film carried on a backing member, with the film being applied to the material to be decorated by being pressed thereagainst, at the same time as heat is applied. After the material has cooled down, the backing member of the foil is removed, leaving decoration, texturing or other patterning on the web of material in question. Such a foil is referred to herein as an embossing foil.
The invention also relates to an apparatus for performing such a method.
It is already known for webs of material in strip form to be decorated with hot embossing foils of the general kind indicated above. The mode of operation in that connection is generally that the web of material, in conjunction with the embossing foil, is passed through a slot between a heated cylinder and a pressure roller, that procedure therefore basically comprising a calandering process However, that process suffers from some serious disadvantages. On the one hand, the operating speeds which can be attained are generally very low because heat has to be applied to the embossing foil and the web of material to be decorated thereby, for a certain minimum period of time if a satisfactory join between the foil and the web of material is to be achieved. In addition, there is the danger that the embossing may turn out to be defective as the action of heat and pressure is generally only over a small, virtually linear region, in consideration of the fact that the pressure as between the foil and web of material to which it is to be applied is produced between a single heated cylinder and a single pressure roller. If the temperature of the embossing heated cylinder is increased, then there is the possibility of either the web of material or the embossing foil suffering from damage as a result. Therefore, the known process is subject to fairly restricting conditions.
In an attempt to improve the above-discussed process, it has been suggested that the web of material to be decorated, together with the embossing foil, may be passed successively through a plurality of gaps each formed by a heated cylinder and a pressure roller. However, that mode of operation resulted in virtually no improvement of substance, in comparison with the process using just a single pressing gap. On the contrary, it was even observed in some circumstances that the embossing results were worse. That was because the material to be decorated and the embossing foil cooled down relatively quickly after leaving a gap between a pressure roller and a heated cylinder, with the result that the materials had to be virtually completely heated up to operating temperature again in the next following gap. Cooling the foil can also have the result that the pattern produced is distorted due to shrinkage in the foil. Such defects in the decoration effect produced are then-so-to-speak fixed when the material and foil then passes through further working gaps.